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| Miyun County is influenced by cold air from the Northwest in spring, autumn and winter while influenced by the warm wet air marine from southeast in summer because it belongs to the warm temperate zone, and continental grassland climate. It is arid and windy in spring, hot and rainy in summer, nice and cool and moist in autumn, dry in winter. The air is better than first grade. |
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Temperature:
Annual average temperature: 10.8¡æ.
The highest temperature: 36.7¡æ. (June 2nd 1986)
The lowest temperature: -21¡æ. (February 12th 1984)
Humidity:
Annual average relative humidity :61©‡ |
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Wind direction:
The prevailing wind: The Northeast and towards the East, frequency 16.2©‡
Annual average wind speed: 2.4m/s, the average wind speed is the fastest in spring; the average wind speed is the lowest in summer.
The fastest wind speed: 17.0m/s, wind speed ESE (July 11th 1986)
Wind direction in Winter: prevailing wind is ENE; less prevailing winds are NE and E.
Wind direction in Spring: prevailing wind is NE; less prevailing winds are E and SW.
Wind direction in Summer: prevailing wind is NE; less prevailing winds are ENE, E and SW.
Wind direction in Fall: prevailing winds are NE and ENE; less prevailing wind is NNE |
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Rainfall:
Annual precipitation: 665.3mm
The largest precipitation per day: 137.0mm (August 25th 1985)
Annual average frost-free time: 176 days
Period of rainfall:
The annual rainfall concentrates on June, July and August and all the precipitation is above 80©‡. |
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Hydrogeology:
The main river is Chaobai River in Miyun County and it leaves the county from south. Chaobai River pours into Miyun Reservoir separately. The water enters into the urban area by Jingmi Channel. The drainage area above Miyun Reservoir is 15788 sq. km; the drainage area of White River is 9000 sq. km and the drainage area of Chao River is 6000 sq. km.
BMIDA belongs to the pediment plain area. The layer of the groundwater is about 20 meters and includes mainly by the sand, and the cobble distributing for single thick floor. The ground water is between 2.5-6.0 meters and gradually changes shallowly from north to south. The general high water mark burying depth in 1.5-4.5 meters, single wells quantity is approximately 5000 cubic meters / day while falls the deep 5 meter .The ground water supplies mainly originates to three aspects the atmospheric precipitation enters infiltrates; the surface water and the agriculture irrigates into infiltrates; Mountainous area bedrock lateral runoff. |
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